They've added a super-political action committee, which can raise unlimited money, to their arsenal. They are targeting races in Republican-leaning states to reduce the odds of Democrats picking off a seat. And they're vetting candidates more carefully, rather than supporting those who simply claim to be part of the movement.

"We've now been through a cycle with wins and a cycle with losses, and you learn from both of those," said Jenny Beth Martin, the national coordinator, of the Tea Party Patriots, a group based in the Atlanta area. "We can go into 2014 with a foundation of understanding of what we're up against."

Such restraint may be vital with control of the U.S. Senate on the line. Republicans need a net gain of six seats to take control of the chamber. Half of the party's 12 incumbents up for re-election this year face primary challengers, many of whom are Tea Party enthusiasts. Business leaders in Texas and Kentucky are rallying behind the incumbents, whose re-elections are safer bets. That leaves little room for error.